1. Field
The present disclosure relates to a display device and an electronic device, and more particularly, to a display device and an electronic device having an infrared touch screen panel and using a housing frame as an optical guide portion.
2. Related Art
In general, a touch screen panel (TSP) is an input device which, if a user presses or contacts a screen with a finger or a pen, recognizes the position of such pressing or touch and transfers the recognized position information to the system. With the spread of smart phones, the TSP has been widely expanded.
The TSP is composed of a touch panel, a controller IC (Integrated Circuit), and driver software, and the touch panel is composed of an upper plate and a lower plate (film or glass), on which ITO (Indium Tin Oxide) is deposited, and serves to grasp the position of signal occurrence that is caused by the contact occurrence or electrical capacitance change and to transfer the grasped position information to the controller IC. The controller IC serves to change an analog signal that is transferred from the touch panel in the form of coordinates that can be presented on the screen through conversion of the analog signal into a digital signal, and the driver software is a control program that implements the touch panel to match the operating systems through reception of the digital signal output from the controller IC.
In accordance with an application technology, the TSP may be classified into a resistance film type, a capacitance type, an ultrasonic type, an infrared type, and an optical type.
The infrared type TSP is a touch screen panel that uses the linearity of infrared rays. The infrared rays that strike an obstacle are intercepted. The infrared type TSP has a matrix structure in which a plurality of light emitting elements LED that emit infrared rays and a plurality of light receiving elements (photodiodes) that respectively correspond to the light emitting elements are arranged to face each other around the panel. If a finger (or a predetermined shape that can make a shadow, for example, an object that is thin and long, such as a bar, a pencil, or a brush (hereinafter referred to as an “object having a predetermined shape”) touches the screen to intercept light, an output of the intercepted portion is deteriorated, and X, Y coordinates of the portion is obtained to determine input coordinates. In this case, a finger or an object having a predetermined shape may be used as an input device. The infrared type TSP has the advantages of high light permeation, high durability, and applicability to a large screen, but also has the drawbacks of high manufacturing cost, low slimming, and low resolution. The infrared type TSP is mainly applied to an ATM device or a kiosk.
According to the display device in the related art that adopts the infrared type TSP, gaps are formed between the light emitting elements and the light emitting elements due to assembly tolerance between the light emitting elements, assembly tolerance between the light receiving elements, and assembly tolerance occurring when the light emitting elements and the light receiving elements are assembled on the PCB. Due to such gaps, a blind zone in which no light exists occurs, and thus even if the finger or the object having the predetermined shape is positioned in the blind zone, the coordinate values may not be properly recognized.
In order to solve this problem, the infrared type TSP in the related art adopts an optical guide portion on which a light diffusion lens is formed. In particular, the infrared type TSP, as illustrated in FIG. 1, is configured so that an optical guide portion 3 of a display device 1 also serves as a support frame that can maintain the strength of the display device 1. Accordingly, the depth of a touch area is minimized to resolve the visual drawbacks, and the number of components is reduced to save the manufacturing cost.
However, in the case of adopting the optical guide portion 3 having the structure as illustrated in FIG. 1, liquid drops D, which may occur due to water or coffee that is spilled on a touch screen panel 5, may be driven onto a corner portion on which the optical guide portion 3 and the touch screen panel 5 meet each other, or may stick to a projection surface 4 of the optical guide portion 3. In this case, light that is emitted from the projection surface 4 of the optical guide portion 3 may interfere with the liquid drops and thus may be unwantedly dispersed in an unspecified direction to cause the occurrence of malfunction.
Further, as another example of malfunction, if foreign substances, such as dust, are accumulated on the corner portion on which the optical guide portion 3 and the touch screen panel 5 meet each other, the projection surface 4 of the optical guide portion 3 may be hidden by the accumulated foreign substances, and thus the light that is emitted from the projection surface 4 is physically intercepted to cause the occurrence of malfunction.
In FIG. 1, unexplained reference numeral “2” denotes a rear cover, “7” denotes a PCB, “8” denotes a light emitting element, and “9” denotes a light receiving element.